A foldable microelectronic assembly and a method for forming the same are provided. One or more packages comprising encapsulated microelectronic elements are formed, along with a compliant layer. The packages and the compliant layer are coupled to a redistribution layer. The compliant layer and the redistribution layer are bent such that the redistribution layer is non-planar.
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1. A microelectronic assembly, comprising:
a multi-layer redistribution layer (rdl) including one or more conductive layers and one or more insulating layers, the rdl having at least a first portion at a first region of the rdl located at one end of the rdl and a second portion separate from the first portion at a second region of the rdl separate from the first region of the rdl, the rdl having two exterior surfaces consisting of a first exterior surface and a second exterior surface;
a first package disposed on the first exterior surface of the rdl at the first portion of the rdl, the first package comprising a first encapsulant;
one or more microelectronic elements coupled to the first portion of the rdl and electrically coupled to one or more of the conductive layers of the rdl, the one or more microelectronic elements disposed within the first package; and
a compliant layer, distinct from the one or more conductive layers and the one or more insulating layers of the rdl, disposed on the first exterior surface of the rdl only at a bend portion of the rdl between the first portion and the second portion of the rdl, separating the first region of the rdl from the second region of the rdl, the compliant layer having an arcuate shape, and the rdl bent at the bend portion to conform with the compliant layer such that the first portion and the second portion of the rdl are non-coplanar.
13. A microelectronic assembly, comprising:
a redistribution layer (rdl) having at least a first portion at a first end of the rdl and a second portion separate from the first portion at a second end of the rdl separate from the first end of the rdl, and including one or more conductive layers and one or more insulating layers, the rdl having two exterior surfaces consisting of a first exterior surface and a second exterior surface;
a first package disposed on the first exterior surface of the rdl at the first portion of the rdl, the first package comprising an encapsulant;
a second package disposed on the first exterior surface of the rdl at the second portion of the rdl, the second package comprising an encapsulant;
one or more first microelectronic elements coupled to the first portion of the rdl and electrically coupled to one or more of the conductive layers of the rdl, the one or more first microelectronic elements disposed within the first package;
one or more second microelectronic elements coupled to the second portion of the rdl and electrically coupled to one or more of the conductive layers of the rdl, the one or more second microelectronic elements disposed within the second package; and
a compliant layer, distinct from the one or more conductive layers and the one or more insulating layers of the rdl, disposed on the first exterior surface of the rdl only at a bend portion of the rdl between the first portion and the second portion of the rdl, separating the first end of the rdl from the second end of the rdl, the compliant layer coupled to the first package to the second package, the compliant layer having an arcuate shape and the rdl having a non-planar shape at the bend portion to conform to the arcuate shape, the first portion and the second portion of the rdl being non-coplanar.
2. The microelectronic assembly of
3. The microelectronic assembly of
4. The microelectronic assembly of
5. The microelectronic assembly of
6. The microelectronic assembly of
7. The microelectronic assembly of
one or more additional compliant layers disposed at one or more additional bend portions of the rdl and extending partially into adjacent portions of the rdl.
8. The microelectronic assembly of
9. The microelectronic assembly of
10. The microelectronic assembly of
11. The microelectronic assembly of
12. The microelectronic assembly of
14. The microelectronic assembly of
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The following description relates to packaging of integrated circuits (“ICs”). More particularly, the following description relates to foldable arrangements for ICs.
The demand for more compact physical arrangements of microelectronic elements such as integrated chips and dies has become even more intense with the rapid progress of portable electronic devices, the expansion of the Internet of Things, nano-scale integration, subwavelength optical integration, and more. Merely by way of example, devices commonly referred to as “smart phones” integrate the functions of a cellular telephone with powerful data processors, memory and ancillary devices such as global positioning system receivers, electronic cameras, and local area network connections along with high-resolution displays and associated image processing chips. Such devices can provide capabilities such as full internet connectivity, entertainment including full-resolution video, navigation, electronic banking and more, all in a pocket-size device. Complex portable devices require packing numerous chips and dies into a small space.
Microelectronic elements often comprise a thin slab of a semiconductor material, such as silicon or gallium arsenide. Chips and dies are commonly provided as individual, prepackaged units. In some unit designs, the die is mounted to a substrate or a chip carrier, which is in turn mounted on a circuit panel, such as a printed circuit board (PCB). Dies can be provided in packages that facilitate handling of the die during manufacture and during mounting of the die on the external substrate. For example, many dies are provided in packages suitable for surface mounting. Numerous packages of this general type have been proposed for various applications. Most commonly, such packages include a dielectric element, commonly referred to as a “chip carrier” with terminals formed as plated or etched metallic structures on the dielectric. The terminals typically are connected to the contacts (e.g., bond pads) of the die by conductive features such as thin traces extending along the die carrier and by fine leads or wires extending between the contacts of the die and the terminals or traces. In a surface mounting operation, the package may be placed onto a circuit board so that each terminal on the package is aligned with a corresponding contact pad on the circuit board. Solder or other bonding material is generally provided between the terminals and the contact pads. The package can be permanently bonded in place by heating the assembly so as to melt or “reflow” the solder or otherwise activate the bonding material.
Many packages include solder masses in the form of solder balls that are typically between about 0.1 mm and about 0.8 mm (5 and 30 mils) in diameter, and are attached to the terminals of the package. A package having an array of solder balls projecting from its bottom surface (e.g., surface opposite the front face of the die) is commonly referred to as a ball grid array or “BGA” package. Other packages, referred to as land grid array or “LGA” packages are secured to the substrate by thin layers or lands formed from solder. Packages of this type can be quite compact. Certain packages, commonly referred to as “chip scale packages,” occupy an area of the circuit board equal to, or only slightly larger than, the area of the device incorporated in the package. This scale is advantageous in that it reduces the overall size of the assembly and permits the use of short interconnections between various devices on the substrate, which in turn limits signal propagation time between devices and thus facilitates operation of the assembly at high speeds.
Packaged semiconductor dies can also be provided in “stacked” arrangements, wherein one package is provided, for example, on a circuit board or other carrier, and another package is mounted on top of the first package. These arrangements can allow a number of different dies to be mounted within a single footprint on a circuit board and can further facilitate high-speed operation by providing a short interconnection between the packages. Often, this interconnect distance can be only slightly larger than the thickness of the die itself. For interconnection to be achieved within a stack of die packages, interconnection structures for mechanical and electrical connection may be provided on both sides (e.g., faces) of each die package (except for the topmost package). This has been done, for example, by providing contact pads or lands on both sides of the substrate to which the die is mounted, the pads being connected through the substrate by conductive vias or the like. Examples of stacked chip arrangements and interconnect structures are provided in U.S. Patent App. Pub. No. 2010/0232129, the disclosure of which is incorporated by reference herein.
Some solutions also include the use of flexible substrates and printed circuits, or folded circuit carriers. One or more v-shaped cuts, for example, can be made in a carrier and in package encapsulant, providing an edge for folding the package onto itself into a quasi-stacked arrangement. Difficulties arise due to mechanical stresses on the substrates and carriers from the bending and folding, which can lead to failure of the circuit or the package.
The detailed description is set forth with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical items.
For this discussion, the devices and systems illustrated in the figures are shown as having a multiplicity of components. Various implementations of devices and/or systems, as described herein, may include fewer components and remain within the scope of the disclosure. Alternately, other implementations of devices and/or systems may include additional components, or various combinations of the described components, and remain within the scope of the disclosure.
Overview
A microelectronic assembly is disclosed, comprising a redistribution layer (RDL), one or more microelectronic elements (IC chips, dies, etc.), and a compliant layer. The one or more microelectronic elements may be packaged (e.g., encapsulated, etc.), and are coupled to the RDL. For instance, the microelectronic elements are electrically coupled to one or more conductive layers of the RDL. The compliant layer is coupled to the RDL adjacent to or near the packages, for example, and can mitigate mechanical stresses of bending or folding the microelectronic assembly.
For example, in various embodiments, the RDL comprises a generally thin, rigid or semi-rigid layer that is potentially brittle. The RDL has a minimal thickness, to redistribute connections from connection points on the microelectronic element(s) to other points along a surface of the RDL, to make connections to carriers and the like. Conventional RDL layers similar to the RDL contemplated herein are typically applied on the surface of a microelectronic device and are too thin and brittle to provide any structural support to the microelectronic device. RDL typically consists of alternating layers of insulator, such as an oxide, polyimide, etc., and conductor, such as copper, aluminum, nickel, etc. RDL is not commonly intended to bend, and will likely crack or break without the support of the compliant layer as described herein.
In various implementations, the one or more packages comprising encapsulated microelectronic elements are formed, along with the compliant layer, and then the microelectronic elements and the compliant layer are coupled to the RDL in a desired arrangement. In alternate embodiments, some components may be formed on the RDL. The compliant layer is formed to an arcuate shape and the RDL is bent, such that the RDL is non-planar. For example, the RDL may be bent to a desired angle (e.g., 90 degrees, or a lesser or greater angle), or the RDL may be bent so that one portion of the RDL is folded over another portion of the RDL, the two portions being substantially parallel.
In various aspects of the disclosure, features may be molded into the package of the microelectronic elements. For example, interlocking features may be molded into one or more surfaces of the packages, the features interlocking when the RDL is folded and the packages make contact in a predetermined arrangement.
In an embodiment, several bends or folds in the RDL may be desirable for an application. In the embodiment, the RDL includes multiple portions, with compliant layers disposed between the portions. Various ones of the portions may or may not include microelectronic elements. In the embodiment, the compliant layers disposed between the portions allow the RDL to be folded or bent at the location of the compliant layers, while mitigating the mechanical stresses associated with the bend. In some implementations, an additional compliant layer may be disposed on an opposite surface of the RDL, opposite a compliant layer. The additional compliant layer further adds to the stress mitigation at a desired fold or bend location. More particularly, As the package(s) are folded, the compliant layer provides a counteracting force along the length of the folding area. This generally guides the RDL into a more gentle arcuate shaped than would be achievable without the compliant layer.
One aspect of the disclosure provides terminal pads, terminals, solder balls, and the like disposed on a surface of the RDL. For example, the terminals may be electrically coupled to one or more of the conductive layers of the RDL, such that the microelectronic assembly can be mounted to another carrier, such as a PC board or the like. In one embodiment, when the RDL is folded, the terminals may be available on the top of the microelectronic assembly structure as well as on the bottom.
Various implementations and arrangements are discussed with reference to electrical and electronics components and varied carriers. While specific components (i.e., integrated circuit (IC) chips, wafers, substrates, printed circuit boards (PCB), discrete components, etc.) are mentioned, this is not intended to be limiting, and is for ease of discussion and illustrative convenience. The techniques and devices discussed are applicable to any type or number of packages, packaged circuits or components, circuits (e.g., integrated circuits (IC), mixed circuits, ASICS, memory devices, processors, etc.), electrical components or groups of components, carrier structures (e.g., wafers, substrates, panels, boards, PCBs, etc.), and the like. Each of these components, circuits, chips, structures, and the like, can be generically referred to as a “microelectronic element.” Further, references to a specific component are also applicable to other types of microelectronic elements, unless specified.
Implementations are explained in more detail below using a plurality of examples. Although various implementations and examples are discussed here and below, further implementations and examples may be possible by combining the features and elements of individual implementations and examples.
In an embodiment, as shown in
A “second region” of the temporary layer 104 and/or 106 includes another portion that is designated or desirable to be folded or bent with respect to the first region, other regions, or with respect to the rest of the temporary layer 104 and/or 106. Accordingly, in the illustrations of
In an implementation, the temporary layer 104 and/or 106 includes one or more additional regions that are designated or desirable to be folded or bent with respect to the first and/or second regions or with respect to the rest of the temporary layer 104 and/or 106 (see
As shown in
In an implementation, the one or more first microelectronic elements 102, the compliant layer 110, and the temporary layer 104 and/or 106 are placed into a mold 112. If desired, the one or more second microelectronic elements 108 are also placed in the mold 112. As shown in
The mold 112 is filled with an encapsulant (e.g., molding, filler, etc.) to form a first package portion 114 corresponding to the first portion of the mold 112. The first package portion 114 fully or partially encapsulates the one or more first microelectronic elements 102. If desired, filling the mold 112 also forms a second package portion 116 corresponding to the second portion of the mold 112. The second package portion 116 fully or partially encapsulates the one or more second microelectronic elements 108. In an embodiment, the encapsulant also encapsulates a portion of each end of the compliant layer 110, coupling the compliant layer 110 to the first 114 and second 116 package portions.
The first package portion 114, the second package portion 116 (if present), and the compliant layer 110 are removed from the mold 112. In an embodiment, the first package portion 114 and the second package portion 116 (if present) remain coupled to the compliant layer 110 by the encapsulant.
As shown in
For the purposes of the disclosure, the RDL 118 includes a first portion and a second portion corresponding to the first region and the second region of the temporary layer 104, 106. Accordingly, the first package portion 114 is coupled to the RDL 118 at a first portion of the RDL 118, and the first microelectronic elements 102 are coupled to one or more conductive layers of the RDL 118. If present, the second package portion 116 is coupled to the RDL 118 at a second portion of the RDL 118, and the second microelectronic elements 108 are also coupled to one or more conductive layers of the RDL 118. In this form, the microelectronic assembly 100 may be folded or bent as desired for its intended application.
In an alternate implementation, the first 102 and second 108 microelectronic elements may be placed in the mold 112 with terminal contacts exposed (not shown). The compliant layer 110 may be placed between the first 102 and second 108 microelectronic elements, and the mold 112 is filled to form the first 114 and second 116 package portions. The compliant layer 110 is coupled to the first 114 and second 116 package portions by the encapsulant. The RDL can be added to the “terminal contact” side of the first 114 and second 116 package portions and the compliant layer 110 after molding.
As shown in
In various embodiments, the microelectronic assembly 100 may be bent or folded in an infinite range of angles (e.g., 0-360 degrees), with respect to the first 114 and second 116 package portions or the first and second portions of the RDL 118. For example, as shown in
For example, in some embodiments as shown in
In an implementation, one or more of the terminal pads 702 disposed on the second surface of the RDL 118 opposite the first portion (or the first package portion 114) are electrically coupled to one or more of the terminal pads 702 disposed on the second surface of the RDL 118 opposite the second portion (or the second package portion 116). In the implementation, the folded microelectronic assembly 200 forms a vertical interconnect structure.
As shown in
Unless otherwise specified, alternative components to those specifically mentioned may be used to implement the techniques described herein. In various implementations, the techniques described herein may be applied to stacks or groups of stacks of packaged microelectronic components 102, 108, or the like.
Referring to
At 908, the process includes coupling the one or more first microelectronic elements to a first portion of a RDL (such as RDL 118, for example), where the RDL has at least a first portion and a second portion, and includes one or more conductive layers and one or more insulating layers. In an embodiment, the one or more first microelectronic elements are electrically coupled to one or more of the conductive layers of the RDL.
At 910, the process includes coupling the compliant layer to a portion of the RDL between the first portion and the second portion of the RDL, the compliant layer partially extending into the first portion and partially extending into the second portion of the RDL.
In an implementation, the encapsulating is performed after coupling the one or more first microelectronic elements and the compliant layer to the RDL.
In various implementations, encapsulating and coupling the microelectronic elements to the RDL includes: depositing the one or more first microelectronic elements at a first region of a temporary layer, where the temporary layer has at least a first region and a second region; depositing the compliant layer at a region of the temporary layer between the first region and the second region of the temporary layer, such that the compliant layer partially extends into the first region and partially extends into the second region of the temporary layer; placing the one or more first microelectronic elements, the compliant layer, and the temporary layer into a mold, where the mold has a first portion corresponding to the first region of the temporary layer and a second portion corresponding to the second region of the temporary layer, and the compliant layer forms a barrier between the first portion and the second portion of the mold.
In the implementations, the process includes filling the mold with encapsulant to form the first package portion, where the first package portion corresponds to the first portion of the mold, and encapsulating the one or more first microelectronic elements. The process includes removing the first package portion and the compliant layer from the mold, with the first package portion coupled to the compliant layer; and coupling the first package portion and the compliant layer to the RDL (if they aren't coupled to the RDL yet). In the implementations, the first portion and the second portion of the RDL corresponds to the first region and the second region of the temporary layer.
At 912, the process includes forming the compliant layer to have an arcuate shape. At 914, the process includes bending the RDL to conform to the compliant layer, such that the first portion and the second portion of the RDL are non-coplanar (or no longer coplanar). In an embodiment, the process includes bending the compliant layer and the RDL such that the first package portion makes contact with the second package portion, and the first and second package portions are parallel. In another embodiment, the process includes bending the compliant layer and the RDL such that the first package portion makes an angle of approximately 90 degrees with respect to the second package portion.
In an implementation, the process includes forming a second package portion (such as package portion 116, for example) adjacent to the compliant layer. The second package portion may enclose a portion of the compliant layer. In an implementation, the second package portion comprises an encapsulant and may include one or more second microelectronic elements (such as microelectronic elements 108, for example). The process includes coupling the second package portion to the second portion of the RDL, and electrically coupling the one or more second microelectronic elements (if present) to one or more of the conductive layers of the RDL.
In various implementations, forming and coupling the second package portion to the RDL includes: filling the mold with encapsulant to form the second package portion, where the second package portion corresponds to the second portion of the mold; removing the second package portion from the mold, along with the first package portion and the compliant layer, with the first package portion and the second package portion coupled to the compliant layer; and coupling the second package portion along with the first package portion and the compliant layer to the RDL. In the implementations, the second package portion may contain microelectronic elements or it may not.
In various implementations, when the second package portion contains microelectronic elements, the process includes: depositing the one or more second microelectronic elements at the second region of the temporary layer; placing the one or more second microelectronic elements into the mold; and filling the mold with encapsulant to form the second package portion, where the second package portion corresponds to the second portion of the mold, and the second package portion encapsulates the one or more second microelectronic elements.
In an alternative implementation, the first and second (if present) package portions may be formed on the RDL. For example, first and second microelectronic elements are placed on the RDL at the first and second portions of the RDL, respectively. Terminal contacts of the first and second microelectronic elements are electrically coupled to one or more conductive layers of the RDL. The compliant layer is placed on the RDL between the first and second (if present) microelectronic elements. The first and second microelectronic elements are encapsulated, forming the first and second package portions on the RDL. The compliant layer is coupled to the first and second package portions by the encapsulant, for example, at each end of the compliant layer.
In an implementation, the process includes molding first features into the first package portion and second features into the second package portion. The process further includes interlocking the first features with the second features when the compliant layer and the RDL are bent such that a surface of the first package portion makes contact with a surface of the second package portion.
In various implementations, the process includes encapsulating one or more additional microelectronic elements to form one or more additional package portions. Additional compliant layers are formed adjacent to the one or more additional package portions. The process includes coupling the one or more additional package portions to additional portions of the RDL, and electrically coupling the one or more additional microelectronic elements to one or more of the conductive layers of the RDL.
Different configurations of a foldable microelectronic assembly 100 or a folded microelectronic assembly 200 than those illustrated or discussed may be possible with different implementations, and are within the scope of the disclosure. The variations may have fewer elements than illustrated in the examples shown in
The order in which the processes are described herein is not intended to be construed as a limitation, and any number of the described process blocks can be combined in any order to implement the processes, or alternate processes. Additionally, individual blocks may be deleted from the processes without departing from the spirit and scope of the subject matter described herein. Furthermore, the processes can be implemented in any suitable materials, or combinations thereof, without departing from the scope of the subject matter described herein. In alternate implementations, other techniques may be included in the processes in various combinations, and remain within the scope of the disclosure.
Although the implementations of the disclosure have been described in language specific to structural features and/or methodological acts, it is to be understood that the implementations are not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as representative forms of implementing example devices and techniques.
Each claim of this document constitutes a separate embodiment, and embodiments that combine different claims and/or different embodiments are within the scope of the disclosure and will be apparent to those of ordinary skill in the art upon reviewing this disclosure.
Mohammed, Ilyas, Haba, Belgacem
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